The major part of the district belongs to the drainage basin of the Volga River. The source of the Volga is located in the district, in the selo of Volgoverkhovye. The district is locates in the southern outskirts of the Valdai Hills, and there is a large lake district in the area of Ostashkovsky District. The biggest lakes in the area are Lake Seliger, with the town of Ostashkov located on its shore, Lake Volgo and Lake Sterzh (parts of Upper Volga Reservoir), and Lake Sig. Both Seliger (via the Selizharovka River) and Sig drain into the Volga, Verkhyaya Volga Reservoir is built in the upper course of the Volga, and the Volga flows through Lake Volgo. Minor areas in the northwest of the district belong to the basin of the Pola River in the basin of the Neva, and rivers in the northeast of the district drain to the Shlina River, also in the drainage basin of the Neva. The Neva drains into the Baltic Sea, and the Volga drains into the Caspian Sea. Thus, the divide between the Atlantic Ocean and the Caspian Sea runs through the district.

On 1 October 1929, governorates and uyezds were abolished, and Ostashkovsky District with the administrative center in the town of Ostashkov was established. It belonged to Velikiye Luki Okrug of Western Oblast.[11][12] On August 1, 1930 the okrugs were abolished, and the districts were subordinated directly to the oblast. On January 29, 1935 Kalinin Oblast was established, and Ostashkovsky District was transferred to Kalinin Oblast.[12][13] During World War II, the district was not occupied by German troops but until 1943 stayed in the immediate vicinity of the front lines.[11] In February 1963, during the abortive administrative reform by Nikita Khrushchev, Kirovsky and Penovsky Districts were merged into Ostashkovsky District. On January 12, 1965 Selizharovsky District (which occupied the same area as Kirovsky District), and on December 27, 1973 Penovsky District were re-established. On 12 January 1965 Andreapolsky District was established in the areas which previously belonged to Toropetsky and Ostashkovsky Districts. In 1990, Kalinin Oblast was renamed Tver Oblast.[13]

Industry dominates in the economy of the district. As of 2014, the industrial output represented over 90% of the GDP. The main industrial enterprise in the district is Ostashkov Leather Factory. Additionally, enterprises of timber, textile, and food industries are present.[16]

The district contains 187 cultural heritage monuments of federal significance (125 of them located in Ostashkov) and additionally 287 objects classified as cultural and historical heritage of local significance (118 of them in Ostashkov). Essentially, the whole center of Ostashkov consists of listed buildings. Other federal monuments include the Nilova Pustyn monastery, located on an island on Lake Seliger, the Novyye Yeltsy Estate in the selo of Novyye Yeltsy, as well as a number of churches in the villages of the district and several acheological sites.[17]

Ostashkovsky District Museum was founded in 1889 and is located in Ostashkov. It has displays on local history and ethnography.[18] In 1986, the Seliger Area Nature Museum was open in the settlement of Rogozha, and in 2002, the Museum of the Source of the Volga was open in Volgoverkhovye.[19]

^Law #34-ZO stipulates that the borders of the administrative divisions of the district match those of the municipal formations the corresponding municipal district is subdivided into. Law #40-ZO contains the list of the municipal formations of Ostashkovsky Municipal District. The counts of inhabited localities are per OKATO.

^The value of density was calculated automatically by dividing the 2010 Census population by the area specified in the infobox. Please note that this value is only approximate as the area specified in the infobox does not necessarily correspond to the area of the entity proper or is reported for the same year as the population.